The Polar Bear as a Biological Indicator of the Environmental Mercury Burden

128 fresh (current) and 18 preserved (museum) polar bear hair samples were subjected to mercury analysis. Mercury levels ranging from <0.5-44.3 ppm were observed in the fresh samples with a geographic distribution showing higher levels in the western Arctic and substantially lower levels in the eastern Arctic and in Hudson's Bay. A similar geographic range and distribution was found in the museum specimens. No correlation can be demonstrated between observed levels and industrial releases of mercury. There is no real indication of increase in general levels over time. The source of observed high levels of mercury in arctic marine fauna appears to be geologic rather than industrial.Key words: mercury, polar bearMots clés: mercure, ours polair

Stable isotope food-web analysis and mercury biomagnification in polar bears ( Ursus maritimus )

Mercury (Hg) biomagnification occurs in many ecosystems, resulting in a greater potential for toxicological effects in higher-level trophic feeders. However, Hg transport pathways through different food-web channels are not well known, particularly in high-latitude systems affected by the atmospheric Hg deposition associated with snow and ice. Here, we report on stable carbon and nitrogen isotope ratios, and Hg concentrations, determined for 26, late 19th and early 20th century, polar bear ( Ursus maritimus ) hair specimens, collected from catalogued museum collections. These data elucidate relationships between the high-latitude marine food-web structure and Hg concentrations in polar bears. The carbon isotope compositions of polar bear hairs suggest that polar bears derive nutrition from coupled food-web channels, based in pelagic and sympagic primary producers, whereas the nitrogen isotope compositions indicate that polar bears occupy > fourth-level trophic positions. Our results show a positive correlation between polar bear hair Hg concentrations and δ 15 N. Interpretation of the stable isotope data in combination with Hg concentrations tentatively suggests that polar bears participating in predominantly pelagic food webs exhibit higher mercury concentrations than polar bears participating in predominantly sympagic food webs.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73930/1/j.1751-8369.2009.00114.x.pd